1. Field of the Invention
The present invention relates to a method of and an apparatus for developing a photosensitive lithoghraphic plate (hereinafter called "PS plate" as required) on which an image is has been exposed.
2. Description of the Related Art
A photosensitive lithographic plate on which an image has been exposed is transported to a photosensitive-lithographic-plate developing apparatus for the purpose of development.
This development is carried out by utilizing a dip method or a horizontal transport spray development method in which a photosensitive lithographic plate is transported to a development tank which accommodates a developer and is then dipped into the developer for development purposes or by utilizing a metering method in which development is effected by coating light sensitive layers of a photosensitive lithographic plate with a predetermined amount of developer which is substantially fresh.
However, in the case of the aforesaid dip method, since a photosensitive lithographic plate needs to be dipped, a large amount of developer must be charged. Moreover, while a number of plates are being developed, the developer gradually deteriorates. Accordingly, the developer which has deteriorated must be replenished with a fresh developer, so that a large amount of developer will be needed. In addition, a device for supplying the replenisher, piping, etc. are needed for the purpose of replenishment, thus the entire apparatus becomes complicated. Furthermore, the developer must be circulated in order to keep uniform the concentration of the developer, and this also leads to the problem of the apparatus being complicated. In some cases, in order to replace a developer which is being used with a fresh developer, some developer may be discarded even though it is still usable. For this reason, it has been impossible to effectively use the developer without any waste.
In the horizontal transport spray development method, since the developer must be circulated, the entire apparatus becomes likewise complicated.
On the other hand, in the case of the metering method, development is always carried out with a fresh developer which has not yet been used. Accordingly, since neither a device for supplying a replenisher for the developer nor a device for circulating the replenisher is needed, the apparatus is simple compared to the apparatus used in the dip method or the horizontal transport spray development method described above.
In the aforesaid metering method, however, when a photosensitive lithographic plate is to be vertically transported in case the plate has light sensitive layers on both side thereof, the PS plate which is transported in the approximately horizontal direction must be turned in the approximately vertical direction. Accordingly, there is a disadvantage in that a guide/transport roller or the like is needed. For this reason, it has been proposed to develop the PS plate while transporting it in the horizontal direction.
However, if the both light sensitive layers of a photosensitive lithographic plate are to be coated with a developer while the plate is being transported in the approximately horizontal direction, the following problem will be encountered. If the surface of the photosensitive lithographic plate on which an image has been exposed faces up, the developer is retained on the surface without being dropped, but if the image-printed surface faces down, the developer will naturally drop. Accordingly, it is impossible to develop the lower surface and it is therefore impossible to reliably develop both the upper and lower surfaces of the photosensitive lithographic plate.